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OCH BLOG

Corals are Not Always Bright and Colorful

Updated: Mar 18, 2022

Along the coasts of California, we can find deep-sea coral reefs in Monterey Bay, the Channel Islands, the Gulf of Farallones, and the continental slopes in the Northern parts of California. The closest one to Orange County (OC) would be the Channel Islands. Merely 25 miles off the coast of Southern California, you can visit the Channel Islands National Marine Sanctuary where you will find a diverse range of marine organisms including the deep-sea corals residing more than 100 feet below the surface. One thing to keep in mind is that the California and OC Coastal areas generally have more rock reefs than coral reefs because of the differences in water temperatures. Compared to tropical and subtropical regions where coral reefs thrive, California’s coast is constantly exposed to cold water coming from the North pole via the California Current. Since corals are sensitive to temperature changes, California waters are not the optimal temperatures for their survival. However, rock reefs are able to withstand lower temperatures.


In the photo below, you can see the effects of ocean acidification on the Lophelia pertusa by comparing it to a healthy, bright red Bubblegum coral on the right. The white coral on the left are corals that have undergone and are still undergoing coral bleaching. If water conditions don’t improve, they will eventually die and appear brown in color.


Bubblegum coral (right) and Lophelia pertusa (left and lower-right white coral), deep-sea corals that are sensitive to ocean acidification. Photo Courtesy by NOAA

Global warming is one of the main causes of the mass coral bleaching events we have seen in the past two decades. This event is believed to be caused by human actions, specifically each individual’s carbon footprint. Carbon footprint is the total amount of carbon dioxide emitted due to the consumption of fossil fuels. Major bleaching caused by unusually warm sea surface temperatures during the summer, occurred in 1998, 2002, 2016, and 2017. The effects of global warming have been magnified due to human activities that involve the burning of fossil fuels, deforestation, industrial waste, and landfills which create the greenhouse effect. The greenhouse effect is the trapping of the Sun’s heat due to thickened layers of carbon dioxide in the atmosphere. In Orange County, dense populations that rely heavily on single transit contribute greatly to carbon dioxide emissions into the atmosphere.


Samples of atmospheric CO2 in ice cores increasing since the Industrial Revolution. Photo Courtesy by Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record

In contrast to shallow-water corals, deep-sea corals don’t need sunlight because they obtain their energy by trapping tiny organisms in passing currents. Typically, coral is classified as a deep-sea coral when they are located below 50 feet; most of the time they are found in even deeper waters about 100 feet. But that doesn’t mean they are safe from bleaching. In fact, deep-sea corals are affected by the main cause of global warming which is greenhouse gas emissions. The most common greenhouse emitted is carbon dioxide, methane, and nitrous oxide. When carbon dioxide is absorbed into the ocean, it chemically reacts with seawater resulting in an increased concentration of hydrogen ions in the water. This process is called ocean acidification. The excess hydrogen ions bond with carbonate ions which decreases the amount of carbonate for marine life such as corals, crabs, oysters, and urchins to use for building their shells and skeletons. This is similar to how acidic substances commonly found in foods, like lemons or oranges, can weaken the outer layer of your teeth.


An increase of CO2 in the atmosphere lowers the pH levels of the ocean, resulting in the dissolution of the pteropod shell. Photo Courtesy by NOAA

Coral bleaching, which is most common in shallow water reefs, is not the death of a coral but rather the corals’ stress response to changes in the environment such as temperature rises, pollution, or over-exposure to sunlight. When these changes occur, corals expel their symbiotic algae called zooxanthellae. These algae are essentially providing food for the corals by providing byproducts of photosynthesis to the corals. Without the algae, the corals are left in a vulnerable state that makes them more susceptible to death. In recent studies, corals have been found to change to neon and brightly pigmented colors, instead of the typical bleached white. Although not much is known about this colorful phenomenon, some say that it may be protecting the corals by acting as a sunscreen. Aside from these recent discoveries of coral behavior, corals can naturally recover from bleaching and regain their algae if conditions improve within a relatively short amount of time.


In the picture above, you can see healthy corals on the left (December 2014) and bleached corals (February 2015) on the right. Photo Courtesy by American Samoa - XL Catlin Seaview Survey

It is important to be aware of recent coral bleaching events because coral reefs are essential to the marine ecosystem. The absence of corals can wipe out entire ecosystems because, without them, fish and organisms residing within the corals die due to the lack of shelter, spawning grounds, and protection from predators. Coral reefs also support the biodiversity of the marine biome by sustaining more than 7,000 species of fish, invertebrates, plants, birds, and marine mammals. Sometimes, it is easy to overlook the importance and incredible benefits that coral reefs provide for us because they are mostly found in the ocean.


The Great Barrier Reef. Photo Courtesy by IBORISOFF | ISTOCK

So what can we do to help these sensitive creatures? A good place to start is to educate ourselves and our community. Another thing that most people can do is to change the type of sunscreen they use while in the ocean, but using regular sunscreen outside natural bodies of water is perfectly fine. Although regular sunscreen is not harmful to humans, the ingredients in sunscreen such as oxybenzone (Benzophenone-3) do not biodegrade and can drift to other parts of the world where it can cause detrimental effects to sensitive marine life in shallow water reefs. A good way to combat this is to switch to products with reef-friendly ingredients such as zinc oxide and titanium oxide. We can also help these reefs by reducing our carbon footprint with simple steps such as using paper and reusable bags instead of plastic and reducing the consumption of non-renewable products.


We hope that after reading this article, you feel like you have some new knowledge and tools and you know you don’t have to be a coral scientist to change the future of our oceans. Every little action will contribute to a healthier planet and a better tomorrow no matter how big or small it may be.

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